Steps to reproduce:

1. Go to Browse > Labels
2. It will take a long to load, and even timeout.

Also general slowness and crashing due to long running SQL queries can be a symptom of this problem.

Workaround

Our developers have created a patch that can be applied to all versions of Confluence 4.2, up to and including 4.2.4. The issue will be resolved permanently in 4.2.5.

How to apply the patch

1. Copy the Label.hbm.xml file attached to this ticket, to <confluence-install>/confluence/WEB-INF/classes/com/atlassian/confluence/labels/. Create the folders if they do not exist.
2. Once this is done, restart your Confluence instance.

Limitations

Because of the nature of the patch, once it is applied, labels on attachments will not show up in popular labels, suggested labels and recently updated labels. This will be resolved in 4.2.5 when the permanent fix is released.

Future-proofing

Once you upgrade to 4.2.5, this patch must be removed. It may cause issues down the track if it is not.